1. Field of the Invention
The invention relates generally to power management techniques for computing systems, generally, and more particularly, the invention relates to effective and efficient and, a dynamic server buffering system for optimizing power consumption in servers while adhering to specified Service Level Agreements (SLAs).
2. Description of the Related Art
The cost of data center server power consumption and the cooling systems to dissipate the generated heat are major expenses in modern data centers where thousands of servers are densely packed in relatively small racks. To maintain effective operation and sustain profitability, it becomes necessary to have power management systems to optimize the power usage with respect to customer requirements. In other words, these power management systems must be able to use minimum power possible and yet be able to satisfy all customer requirements. It is well established that a typical server consumes a relatively high amount of power even it is idle, due to chip leakage current and other supporting components such as disk drive and network gears. Turning system off and direct all traffic to a subset of available servers during non-peak hours is a common approach to save power during periods of low traffic. Current technologies for server shutdown are mainly based on actions of system administrators, by manual operation or/and based on some simple policies. Based on their experiences and workload history, the system operators may shut down systems for an extended period of time. In doing so, these system operators must consider the possibility of sudden increased traffic load and in most cases, usually over-provision to account for the worst case situations in order to maintain customer satisfaction. The amount of effort for the system administrators, and the priority of data center to satisfy customer requirement over the cost of power consumption negate the effective use and benefit of these power management systems.
New power management strategies which turn on and off servers based on real time or near real time workload has been investigated. It is obvious that there is a finite cost of shutting down a system and turning it back on. The amount of time to power down/up and restore active applications means lost time for real work and usually maximum power is used to power on/off a server, not to mention the frequent repeated power on/off cycle increases the wear-and-tear of these servers, resulting in higher failure rate. Due to the time lapsed in restoring a server from shut-down state to fully available for use, usually from 1 to 5 minutes, depending on system applications and configurations, power on a shut-down server may not react fast enough to the sudden increased traffic demand, resulting in frequent violation of customer SLAs. In addition, no customer or data center manager want to see their servers spend most of its productive time in repeat turn on/off. All these potential problems prevent this power management strategies from being widely used.
It would be highly desirable to provide an autonomic, adaptive and dynamic server buffering system for server power on/off to optimize power consumption, and at the same time, guarantees customer satisfaction by satisfying customer SLAs.